Volume control combining system



March 15, 1932.

J. B. MOORE VOLUME CONTROL COMBINING SYSTEM Filed Nov. 16, 1928 INVENTOR'rIN B. BL

MOORE ORNEY Patented Mar. 15,` 1932 UNITED STATES PATENT OFFICE JOHN B.MOORE, 0F RIVER-HEAD, NEW YORK, ASSIGNOR TO RADIO CORPORATION 0FAMERICA, A CORPORATION OF DELAWARE VOLUME` CONTROL COMBINING SYSTEMApplication filed November 16, 1928. Serial No. 319,767.

This invention relates to diversity reception, and more particularly tovolume contro'l therefor.

v having dierent fading characteristics, the

energies from which are finally combined together. The volume of thereceived energy 1s apt to vary between the extremes of almost completefading at all of the antennas to no fading at any of the antennas. Toovercome this it has been proposed to equip the receivers for theantennas each with a volume control, but this, in additionto therequirement of a considerable number of volumecontrols, suffers from twogreat disadvantages. One applies to code or speech-simulating signals,and is that the amplifiers of those antennas at which fading isprevalent are given increased gain, in consequence of which the noiselevel of the combined energy is greatly increased. The other appliesmore particularlyto speech-simulating signals, and is that the amplifierof an antenna at which the car-l rier is fading, while the sidebandsIare not, is given increased gain, vin consequence of which thedistortion resulting from the beat between the sidebands is greatlyincreased.

To overcome the foregoing difculties is the primary object of myinvention, which I attain by simultaneously controllingthe gain in theamplifiers of the separately collected energies all in response to thevolume of the combined energy. In this manner the amplifiers experienceequal changes in gain, so that the energy from an antennaat which nofading is present retains itsv magnitude relative to the small energy atantennas lo- L e cated at fading points, and dominates such energy,thereby improving the quality of the combined energy.

When dealing `with energies ,of sufficiently high frequency so that thephases of the received energies at the different antennas fiuctuaterelative to one another, even though Y of like constant frequency, it isnot feasible to combine the received energies directly together, and insuch case my inventionv includes separately detecting the amplified "ienergies, combining the detected energies so that the combination issubstantially independent of the relative radio frequency phase atV thedifferent antennas, and coni trolling the gain in the stepl ofamplification of all of the collected energies in response to the volumeof the combined detected energy,

f as Well as utilizing the combined energy to obtainthe desired signal.

My invention is more completely described in the followingspecification, which is accompanied by a drawing the single figure ofwhich is a wiring diagram for a preferred form of my invention.

Referring to that figure there are a plurality of diversity antennas 2,4 and 6, which are either geographically spaced, or located in differentplanes of polarization, or in `any other manner given dierent fadingcharacteristics. These antennas are coupled by transmission lines 8, 10and 12 to a plurality of radio frequency amplifiers 14, 16 and 18. Theoutput from each of these amplifiersY is coupled to means to heterodynethe radio frequency energy to energy of intermediate frequency,indicated by the rectangles 20, 22 and 24. These means may comprise asource of locally generated energy of relatively high frequency and aseparate heterodyne detector, or a single autodyne circuit in which theelectron emission tube which functions as an oscillatoralso acts as adetector for combining the received and locally generated energies. Theresulting energy of intermediate frequency is amplified in intermediatefrequency amplifiers 26, 28 and 30; The amplified output is fed todetector tubes 32, 34 and 36, across the output circuit of each of whichthere is connected one or more low pass filter sections 38, 40 and 42,for by-passing the radio frequency components of the rectified energies.Y

rlhe signal components of the rectified energies are fed through leads44, 46 and 48 `to a common lead 50, in series with which a source olirect sniple, by conn ec'tiiig tte coupling impedance The circu :indvolume control impedance in series, and rouii-l tlie Jiine c iistuntcond inser and volume conl e tiel impedance in parallel, but i believethe firreingencnt illustrated ii tlie drawing is the moet lesireble one.

l clfiiin: si l. 'E lie inetliod of eiversity r ception Wliicli 1 fincludes siinultii'ieouslv meshing a plurelit f collections ofrelatively `linrncreristics, seperately 5l i: ciesii su rily Aceleeeeenergies, separately Y i i e die ainplifed energies producing controlini iedsnce :i la: d IES connected to unidiieetionel unduletory energy,b 1S mieli are ceiifombining` the unidirectional energies, conn ltrolling` the `frein in tlie aforesaid step of a1ntu s pliczition n.plurality of the collected enli li ergies in resp-e ise to the volumeo1n the coino' biiied unidirectional energy, and translating to Cliecombined energy.

2. Tl e method of diversity reception ivliicli includes collecting` theredieted energy at e plurality oi spaced points, seperately enr providediii pz pi yin' Jlie collected energies, seperately circuiteros ce i theeiiplilied energies to obtain inipedcnce 68 the in C; undulatoryiiiiidir xctionzzl energy, combining tube 'TO coupled tlie detected un'1'rectionnl energies, controlelectrode of' tlic i if li Afrein in theaforesaid step of ampliroin npo'eiitizi the liciition of a plurality oftlie collected enercoupling impei conn zgies in response to the volumeof the comdenser 24. Elie l'iined energy, end utilizinigT the combineduni- 70 may lie fu tional energy.

einplilier The inetliod et diversity reception Wliicli collectingl theradiated energy et zi lity of spaced poi its, separately empli- -yingand lieterodyniiig tlie collectede ergies to obtain :iinpliin edenergies of intermediate frequency, separately detecting the amplifiedeneigg'es to obtain unidirectional unfi `fitorj; energy, combining` thedetected l. rectionzil iinduletory energies, controling tlie @ein in theaforesaid step of :impliienticn or" ezicii of the collected energies in:espoiise to the volume of the combined eni, .d utilizingv the combinedenergy for picture tra i stati n, or oLier It sliould lve i;

rality ol aiitcnnf teristies, pliii coupled thereto, trol responsive toenergy from tlie rece Y controlling the finin.

ergies substeniillw." indepei d 4,-. 'llie combi nation with a diversityreceivrndio frequency pliese at the ing system comprising e. pluralityof enten ma i e provided inem nes of different fedine` characteristicsand a the amplified ener io eonilniie plurzi 'cy or amplifying'receivers coupled the amplified ener., es c ieu lwtu thereto, commonvolume control respontiie volume of tlie combined unidinil undulitoryenergy from the receiv- Aor siniultinieously controlling the ainpl1- forvolume control end exact number of giving); tliein istics, are not ine-f on gein in ell of the receivers, in order heterod *ne tli re i teredii e tlie noise level when the sioinel fades l a 1 n s n ineens tesinnliiij tue res n et :i receiving" point :ind/or the distortionrefrequency energy V1s eiitiielu,y eg sultinfr from tlie beet betweensidebands Wlienused,tlie voli, eccntrel ii'isjv i vili-cn cfirrier fades:it a receiving point to eitliei tlie riiiiiio frequency intermediateiii:Y i Well to both particule-l oiin for translating the combineduniiinc'liiletory energies.

rsity receiving system comprisplurality et antennas of different fadindof tie cori erecteristics, :i plurality of amplifiers tion circuit, me.ed thereto, ineens to seperately detect the amplified energies therebyobtaining uni* directional undulatory energies, means to combine thedetected unidirectional undulatory energies, a common volume controlresponsive to the. combined undulatory energy for simultaneouslycontrolling the gain in a plurality of the aforesaid amplifiers, andmeans to utilize the combined undulatory energy for translation.

6. A diversity receiving system comprising a plurality ofV spacedantennas, a plurality of amplifiers coupled thereto, means to separatelydetect the amplified energies to obtainV unidirectional undulatoryenergies, means to combine the detected unidirectional energies, acommon volume control responsive to the combined energy forsimultaneously controlling the gain in a plurality of the aforesaidamplifiers, and means to translate the combined unidirectional energy.

7. A diversity receiving system comprising a plurality of spacedantennas, a plurality of amplifiers and means to heterodyne the receivedenergy to obtain amplified intermediate frequency energies coupledthereto, means to separately detect the amplified energies to obtainunidirectional undulatory energies, means to combine the Vdetectedenergies, a common volume control responsivevto the combined energy forsimultaneously controlling the gain in each of theaforesaid amplifiers,and means to translate the combined unidirectional energy.

8. A diversity receiving system comprising a plurality of spacedantennas, a plurality of amplifiers coupled thereto, 'a plurality ofd'etector tubes for detecting the amplified energies, a source of anodepotential coupled to all of said detector tubes, a volume controlimpedance connected in series with said source of anode potential, acondenser cooperating with the impedance to establish the time constantof the volume control action, a connection from the volume controlimpedance to the control electrodes of the tubes of each of theaforesaid amplifiers for so varying the amplification gain therein asWill tend to keep the combined energy constant, a coupling impedancearranged in circuit with the volume control impedance to obtain aportion of the combined energy for utilization, an amplifier coupled tothe coupling impedance, and a utilization circuit coupled to theamplifier.

9. A diversity receiving system comprising a plurality of spacedantennas, a plurality of amplifiers coupled thereto, means to separatelyheterodyne the received energies to obtain energies of intermediatefrequency, means to separately amplify the intermediate frequencyenergies, a plurality of detector tubes for detecting the amplifiedenergies, a source of anode potential coupled to all of said detectortubes, a volume control impedance connected in series With said sourceof anode potential, a condenser cooperating with ther impedance toestablish the time constant of the volume control action, a connectionfrom iso

